I have been reading Sherrilyn Kenyon's multiple series for quite some time now, and recently read this one. This isn't one of her Dark-Hunter novels, but the main character has made cameos in quite a few of her other books. Julian of Macedon has been stuck in a book for thousands of years, only allowed to leave when a woman completes a spell, and only able to do whatever it is she wants from him (normally as a sex slave) until she is over him and sends him back into the book. Along comes Grace, tricked into freeing him by a well-meaning friend.
This is, of course, a romance novel, so there are a few more erotic parts to the story, but I really get into the storylines the author uses. She bases a lot on Greek/Roman, Atlantean, and other mythology.
All of her series are easy to read, involving, and entertaining. She's got a series about (essentially) vampires (the Dark-Hunter series), one based on dream mythology (the Dream-Hunter series), secret agents (the BAD series), and a sort of King Arthur-type (I think it's called the Lords of Avalon).
Sherrilyn is a very entertaining author and I plan to try to catch up on the one's I've missed and keep up with the one's she's still working on.